Association between serum vitamin A levels and molecular tumor subtypes in breast cancer patients undergoing radiotherapy

Abstract

Objective: To evaluate the association between serum vitamin A levels and tumor characteristics in patients with breast cancer undergoing radiotherapy, focusing on hormone receptor status and the triple-negative subtype. Methods: Prospective cohort study conducted between February and June 2025 including 50 women with breast cancer who underwent primary surgery and were referred for radiotherapy at an oncology center in Rio de Janeiro, Brazil. Clinical and lifestyle data were collected. Serum vitamin A levels were measured by high-performance liquid chromatography before radiotherapy. Deficiency was defined as <0.30 mg/L. Statistical analyses included t-tests, chi-square or Fisher’s exact tests, and relative risk (α=5%). Results: Mean age was 54.6 ± 12.2 years; 26% had vitamin A deficiency. ER-positive and PR-positive tumors showed higher levels than negative tumors. Triple-negative breast cancer showed the lowest mean levels and highest deficiency prevalence (RR=3.43). No associations were found with BMI, smoking, alcohol use, HER2 status, or prior chemotherapy. Conclusion: Vitamin A deficiency was associated with hormone receptor-negative tumors, particularly the triple-negative subtype.